else operator
The left-associative, binary else operator is used to provide a default value
when it's left operand is null.
Usage
void m(String? s) {
String s2 = s else "";
}
Description
Definition
The else operator is defined in terms of an if expression as follows
if (exists lhs) then lhs else rhs
See the language specification for more details.
The then/else idiom
The then operator is often used with the else operator to emulate
C's ternary operator cond ? when-true-expr : when-false-expr, like so
T|F result = cond then whenTrueExpr else whenFalseExpr;
Compared to if expressions
Distinct from the then/else idiom Ceylon has a separate if expression:
if (cond) then whenTrueExpr else whenFalseExpr;
The if expression is more powerful than the then/else idiom, since it
supports flow typing of is, exists or nonempty conditions to the branches
Type
The result type of the else operator is given by the type expression Lhs&Object|Rhs, where
Lhs is the type of the left hand operand and
Rhs is the type of the left hand operand.
